The present invention relates to a casing brush for use in oil and gas wells.
When the work is conducted on a well casing the tubular casing members are stacked end-to-end and lowered into the well bore. New casing segments often have imperfections on the interior surfaces of the tubulars; old casing segments often have accumulated debris that clings to the inner walls. When production devices are run through the casings they scrape the sides of the casing and cause the debris that is on the casing to pile up downhole, which can eventually jam up the lowermost casing segment. With older pipes, the problem is also of a significant buildup of ferrous debris, such as bits and pieces of metal generated during drilling of a well. While some of the metal debris can be retrieved with magnetic retrieval tools, other obstructing pieces may not be removed from the interior walls of the casing to allow smooth operation of the downhole tools.
Conventionally, the interior of the casing can be cleaned with a scraper, which literally scrapes the walls of the casing to dislodge residue adhering to the walls or with brushes, which have flexible bristles that contact the walls of the casing and brush off the undesirable debris. Some of the brushes have bristles secured on the outer faces of cylindrical bodies and arranged in parallel axial vertical or horizontal rows. Some of the known devices use outwardly biased bristle members mounted on a cylindrical mandrel, with internal springs forcing the bristles to come into contact with the interior wall of the casing. The brush tools are usually pushed inside the casing, applying vertical force to the debris without rotating the brush in the casing.
However, conventional brushes tend to leave some of the debris on the surface. Particularly troublesome is the area of attachment of two casing segments, which are usually secured by exterior collars. The line of connection between the two casing segments tends to accumulate bits of extraneous material in the crevices formed at the joint line. These areas are more difficult to dislodge without several trips downhole.
The present invention contemplates elimination of drawbacks associated with the prior art and provision of an improved casing brush tool, which can be incorporated into a drill string and run downhole for cleaning the interior of the casing and substantially reducing the time required for cleaning the well casings.